What would happen if certain religious practices were outlawed?

Ones that Society did not like or want to hear about. Would that stop these beliefs from being practiced? Terrorism is illegal in the USA, so Fundamentalist Christianity does not have terrorist problems. Yet in the Middle East, Terrorism is allowed in the name of Islam. The only real difference between Fundie Islam and Fundie Christianity have some different foundation and dogma's. However they have the same basic morals, and values.